Steam-boiler furnace.



No. 811,626. PATENTED FEB. a, 1906. B.E.ELDRED.

STEAM BOILER FURNACE.

APPLICATION FILED NOV. 18, 1904.

UNITED STATES PATENT OFFICE.

BYRON E. ELDRED, OF BRONXVILLE, NEW YORK, ASSIGNOR TO COMBUS- TIONUTILITIES COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

STEAM-BOILER FURNACE;

Specification of Letters Patent.

Patented Feb. 6, 1906.

To all w/wm it may concern.-

Be it known that I, BYRON E. ELDRED, a citizen of the United States,residing at Bronxville, county of Westchester, State of New York, haveinvented certain new and useful Improvements in Steam-Boiler Furnaces,of which the following specification and accompanyin drawing illustrateone form of the invention which I now regard as the best out of thevarious forms in which the invention may be embodied.

This invention relates to steam-boiler furnaces; and its object is toappl the combustion process described in my Enited States Patent No.692,257 to the generation and heating of steam. In that patent a longvoluminous slow-burning com aratively cool flame is produced by passingtlirough the fire a small portion of the waste products of combustion incompany with a predetermined proportion of air. In a steam-boilerfurnace It is found that special provisions are necessary to prevent thecontact of this slowburnlng flame to any great extent with therelatively cold boiler-surfaces, which would chill it and arrest itscombustion. Consequently the ordinary boiler-furnace designed to producea short flame is not suited to carry out the present invention. To avoidsuch contact until the continuance and eventual completion of combustionare insured, use is herein made of two expedients, one of which consistsin the arrangement of refractory heat-retaining surfaces in suchrelation to the boiler as to keep the flame-in its initial stages awayfrom contact with the boiler, while the other consists in using for alike purpose a gaseous jet or jets, such as airjets, so directed as toblow the flame away from the boiler. The jets have the further functionof intensifying the combustion at a remote point. There is also employeda special arrangement of refractory reverberative surfaces heated by theflame and insuch relation to the boiler as to radiate a large amount ofheat thereto. The arrangement of the refractory surfaces and thearrangement of the air-jets in combination therewith are such as tosubject the flame to a reasonably high temperature for quite a eriodafter ignition, and thus prevent the ormation of smoke from thepremature chilling of the hydrocarbon gases of distillation. .Thu's issecured a practically complete combustion.

The flame is carried out of substantial contact with the boiler surfacesduring the period of its incipiency, such a flame being consideredincipient so long as its combustion is so incompletel advanced thatcontact with the cold boi er-surfaces would destroy or substantiallyarrest such combustion. A slow-burning and inflated flame is produced bypassing a regulated amount of products of combustion, together with anair-draft, through the burning fuel on the seat of combustiori, whichmay be a grate or any other form of burner for fuel. The products ofcombustion here, as in my patent hereinbefore acknowledged, have adouble function. The contained carbon dioxid in part reacts with thefuel, entering into an endothermic reaction with the burning carbon,which it oxidizes to carbon monoxid with absor tion of heat, itself alsobecoming converte into monoxid, and thereby produces a body ofinflammable gas, and in part it acts like the nitrogen, generallyforming most of the residue of the products of combustion to inflate andrender slow-burning the gas so produced. The gaseous mixture and the airwhich passes through the fuel with it unchanged together form a longinflated flame. The endothermic reaction at the grate operates toprotect metal arts and also to reclude the formation of c inker, whilethe eat so absorbed is again liberated when the gases are burned furtheron. The rate of combustion of this long flame is susceptible of perfectcontrol, and it is intended to be so regulated that most of thecombustion will take place as the mixture passes through a heated zoneformed by a refractory walled fire-chamber and be completed by anauxiliary air-feed playing upon the flame and heating it down into areversed reverberatory arch.

It has heretofore been proposed to bring back the whole body ofstack-gases and pass them through the fire in an attempt to burn smokeand unconsumed gases; but this is obviously im ossible, since the gasesare greatly expanded y heat above the original volume of the airandfresh air must be continually added to maintain the heat of the fire. No substantial benefit could be had along these lines by burning up onlya small part of the unconsumed products, and it does not appear to havebeen reco nized that the premature cooling by the boi er-surfacesgreatly in- ICC creases the proportion of unconsumed gases and defeatsthe very object sought. It would furthermore be dangerous to returncombustible gases in company with air to the ashpit. It has also beenproposed to create a very intense combustion in a furnace separate fromthe boiler, using stack-gases returned through the grate and heating theboiler only with hot gases from a very hot fire; but gases are very poorcommunicators of heat, and it is. highly inefficient to dispense withthe radiation from an intensely-heated fuel-bed and from a hot flame.The present invention utilizes very largely the radiation upon theboiler from flame and from refractory surfaces. Contrary to the usualaim and practice of carrying an intensely-hot fuel-bed and burning allthe gases in as short a distance therefrom as possible this inventionproceeds upon the theory proven by experience with the process of theaforesaid patent that fuel, especially a bed of coal, can be moreefliciently burned and used b keeping the fuel-bed comparatively cool ancarrying the flame more fully into the region of the materials or objectupon which it operates, special means being required when that object isa boiler to prevent premature chilling of the diluent inflated flame.

The accompanying drawing represents a vertical longitudinal section of ahorizontal return tubular boiler provided with a furnace whoseconstruction and operation embody the principles of the presentinvention.

1 is the boiler, beneath the forward end of which is a fire-box havinggrate 2, fire-chamher 3, and ash-pit 4, with the usual doors kept closednormally to secure a forced draft.

5' is the bridge-wall.

6 is the main chamber beneath and at the rear of the boiler,communicating with the rear ends of the boiler-flues, and 7 is thestackplonnecting with the forward ends of said ues.

The roof of the fire-chamber is bricked over at 8 by an arch extendingpart way the length of the boiler. This arch might be extended furtherto the right than it is shown or not so far, depending upon the designof boiler and other conditions.

In the stack is a damper 9, and below this the inlet to a pipe 10,running to the ash-pit for returning a small portion of the products ofcombustion under the grate, these being drawn back by a fan-blowe 11,whereby normally an artificially-accel rated draft is furnished to thefire. Air for supporting combustion is supplied through an inlet 12 tothe pipe 10 back of the fan, and the relative proportions of air andstack-gases are controlled by valves 13 14 in the air branch and trunkof the pipe. I have also shown means for exercising automatic control ofthe amount of diluent going to the ash-pit by a piston 15, receivingthrough pipe 16 steam-pressure opposed to a spring 17, said istoncontrolling the valve 14 and also the t rottle 18 of the engine 19,which drives the fan, the arrangement being such that increase ofsteamressure beyond a certain point calling or a cooler fire opens valve14 to increase the relative amount of diluent and closes the throttle toslow down the fan and the draft which it furnishes.

At 20 is a nozzle in the arch 8 receiving compressed air through a pipe21 from a compressor 22 and directing it in a jet across the path of theflame from the fire-box and against refractor reverberative surfaces 2324. This air may be preheated by any suitable expedient.

In the operation of the apparatus'a relatively small quantity of thetotal stack-gases is drawn back by the fan 11 and passed through thefire on grate 2, accompanied by a quantity of .air definite inproportion and preferably sufficient to maintain a substantiallycomplete combustion. From the fuelbed emanates a voluminous slow-burningflame which at first is kept from contact with the boiler-surfaces bythe arch 8, this flame being inflated by the neutral stack-gases, whichretard the combination of the air and combustible. The heat-retainingcharacter of the surrounding region insures the. maintenance of ignitionand an increasing temperature, and the jet from nozzle 20 agitates thegases and promotes their final combination within a restricted area,affording a culminating high temperature, which is assumed by the gasesand by the reverberative surfaces at the bottom and rearof the chamber6. An additional function of the jet is to keep the products ofcombustion away from contact with the boiler until combustion issubstantially complete, the extent of this effect, as wellas of theagitating effect, depending somewhat on the number and velocity of'thejets. I thus succeed in maintaining a cool fire-box with obvious economyin fuel and repairs, reduction of clinker formation, less tendency tothe formation of smoke or dust which arises from physical disintegrationupon stoking a hot fire with fresh fuel, while at a later point I securethose temperature conditions which are conducive to a maximumevaporative effect. For this purpose the contents and reverberativesurfaces of the chamber 6 ITO lying'near the entrance to theboiler-flues are most potent. In addition I have furnished the properconditions for the prevention of smoke, as hereinbefore set forth.

The fire is automatically dampened through an increase in thesteam-pressure by 'an increase in the relative quantity of stack-gasesor b slowing the fan, or by both influences com ined, and this withoutthat chilling effect and loss of economy which result from a cold-airdraft over the surface of the fire.

It is of course understood that various modifications are permissible inthe actual embodiment of the ideas herein set forth.

One of the advantages of my invention is that it enlarges the usefulnessand decreases the expense of operating and repairing automatic stokers,particularly those employing underfeed and a forced air-draft but assuch appliances are familiar in the art it is unnecessary to hereillustrate an example.

It maybe added that my rocess cuts down the amount of excess air WllCl'l it is customary to pass through the fire and for a part of thisexcess substitutes stack-gases or other suitable diluent. It will beevident that since a substantially constant quantity of these gases iscontinuously making the circuit the increase of volume due thereto doesnot represent wasted heat energy, as it does in the case of excess airgoing up the stack. It therefore becomes possible to operate with astrong forced draft Whenever it is desired to increase the steamingcapacity of the boiler without any danger of burning out the metasurfaces or otherwise decreasing the life of the fire box.

What I claim as new, and desire to secure by Letters Patent, is-- '1.The combination of a furnace for burning fuel havin a seat ofcombustion, means to pass throug 1 said seat a fixed gaseous diluentwhich will elongate and mflate the flame and retard its combustion, asteamboiler within radiative reach of the flame, and means for carryingthe elongated flame out of substantial contact with the boiler-sun facesduring its incipiency.

2. The combination of a furnace having a refractoryroofedcombustion-chamber,means to roduce a long slow-burning flame therein inated with waste stack gases passed through the seat of combustion, and asteamboiler within radiative reach of the flame.

3. The combination of a furnace havin a seat of combustion, adraft-chamber anterior thereto and supplying draft through the seat ofcombustion, and a Waste-gas outlet, a return conduit connecting saidoutlet with said draft-chamber and having a mechanicaldraft-accelerator, means to supply air to said draft-chamber, asteam-boiler located over said seat of combustion and heated by thefurnace flame and gases, and a refractory wall roofin the furnacebetween said seat and the boi er for separating the flame from theboiler.

4. The combination of a furnace having a seat of combustion, means toass products of combustion through the fuel seat to elongate the flame,a steam-boiler within reach of the elongated flame, one or morejet-outlets in the roof of the combustion-chamber so directedas to blowthe flame away from the boilersurfaces at a point remote from thefuel-seat, and means to force a gaseous pressure fluid through saidjet-outlets.

5. The combination of a furnace having a grate, a combustion-chamber andan ash-pit, means to supply an artificially-accelerated draft-current ofair and stack-gases to said ash-pit, a refractory wall roofing saidcombustlon-chamber, a steam-boiler, one or more jet-outlets located inthe upper part of the combustion-chamber between the grate and theheating-surfaces of the boiler and so directed as to carry the flameaway from the boiler, and means to supply air to said jetoutlets.

6. The combination of a furnace having a seat of combustiommeans tosupply to said seat a forced-draft current of air and diluent productsof combustion to elongate and inflate the flame, a boiler, and aflame-channel included in the furnace and having a refractor surface inheat-radiatin relation to the boi er and provisions whereby the flame iscarried away from the boiler into contact with said surface.

7. The combination of a furnace having a seat of combustion, means tosupply to said seat a forced-draft current of air and diluent productsof combustion to elongate and inflate the flame, a boiler, and aflame-channel included in the furnace and having a refractory surface inheat-radiating relation to the boiler and one or more air-jet outlets onthe boiler side of said channel directed toward said surface.

8. The combination of a steam-boiler, a furnace having a seat ofcombustion and a flame-channel roofed with refractory material betweensaid fuel-sea-t and the heatin surfaces of the boiler, means to su plyprod nets of combustion and air tl1rougl i saidfuelseat to produce anelon ated slow-burning flame, and means to locally agitate the flamesubstantially at the beginning of said heating-surfaces.

9. In a steam-boiler furnace the combination of a boiler, a fire-boxtherefor, means to supply air and a neutral diluent to the fire in suchmanner as to elongate the flame, means to substantially complete thecombustion of the elongated flame at a definite or predetermined pointremote from the fire-box and in radiative relation to the boiler, andmeans to maintain the flame in a surrounding reverberative influenceanterior to said point and out of substantial contact with the boiler.

10. In a steam-boiler furnace the combina tion of a boiler, a fire-boxtherefor having a seat of combustion, means to supply air and productsof combustion through said seat, a refractory roofed chamber between thefirebox and the flues of the boiler, and means to supply an interceptingjet of air to the flame issuing from said chamber.

11. The combination of a boiler, a furnace having a seat of combustion,means to supply air and products of combustion throu 11 said fuel-seat,a refractory roofed flame-c annel IIO between said seat and theheating-surfaces seat of combustion, means to produce a long voluminous,slow-burning flame by inflation with waste stack-gases passed throughthe burning fuel and means to keep the long flame from contact with therelatively cold boiler-surfaces while combustion is incomplete, combinedwith refractory reverberative surfaces in radiating relation with thevaporizing-chamber of the boiler, heated by the flame and serving tomaintain its ignition.

13. The combination of a horizontal return tubular boiler having a gasoutlet or flue at its forward end, a fire-box under the forward part ofthe boiler having a seat of combustion, flame and gas passages extendingrearwardly from the fire-box and forwardly through the boiler to theas-outlet, a refractory wall roofing the flreox between it and theforward part of the boiler, and means to pass products of combustion andair in predetermined proportion through said seat to elongate the flame.

14. The combination in a boiler-furnace of a support for burning solidfuel, means for supplying and passing through said support a neutralgaseous diluent in such manner as to inflate the flame and cool thefuel-bed, a

boiler within heat radiating reach of the flame, and means to keep theflame from contact with the boiler during its incipiency.

15. In a steameboiler furnace the combination of a boiler, a fire-boxtherefor having a seat of combustion, means to pass through said seat adraft-current of air and neutral stack gases, and means controlled bythe steam-pressure for automatically varying the composition of thedraft-current.

16. In a steam-boiler furnace the combination with the furnace of meansfor supplying air and for supplying stack-gases in the draft furnishedto the fire, and means controlled by the steam-pressure for concurrentlyvarying the volume and composition of the draftcurrent.

17. In a steam-boiler furnace, the combination of a boiler, a refractorywalled firechamber, an inverted reverberatory' arch beneath the boiler,means for producing an inflated slow-burning flame in the fire-chamher,air-introducing means for beating said flame down into the arch andcompleting its combustion, and means for carrying the resultant flameproducts into heat-radiating relation with the boiler.

In witness whereof I have hereunto set my hand this 25th day of October,A. D. 1904.

, BYRON E. ELDRED.

Witnesses:

R. M. PrERsoN, A. M. SENIOR.

